In our body, many new cells are produced every day, and accordingly, a large number of old cells die. In order to maintain a suitable number of cells in various tissues in the body, neonatal and death need to achieve a dynamic balance. Apoptosis, a mechanism of programmed cell death that is precisely controlled by genes, plays an important regulatory role in this regard. In addition, it can remove unwanted cells and promote human development, such as the formation of human fingers and toes during the embryonic period. It can be said that apoptosis does not work in the body all the time. The protease Caspase (caspase) present in cells is the ultimate performer of apoptosis and can break down cells into tiny fragments. When a cell is limited, the outer molecule transmits a death signal to the cell by contacting it with a protein receptor on the cell surface. The mitochondria release cytochrome c and activate caspase, thereby disintegrating the cell. The distance is very long, and the death signal is transmitted from one end of the cell to the other. Previous studies have found that the death signal molecule in the cell, activated caspase, always passes from one or several scattered origins to all corners, allowing the cells to reach a globally consistent state of apoptosis. However, the specific process of communication has not been revealed by experiments. A very natural assumption is the diffusion phenomenon, in which molecules are produced in a specific area and transferred to a low concentration area until they are evenly distributed. In general, somatic cells do not exceed 20 microns in diameter, and death signals can be transmitted from one end of the cell to the other by diffusion in a matter of seconds. However, since the diffusion rate will gradually decrease as the concentration difference decreases, for some large cells, such as the thigh muscle cells up to 20 cm, the signal transmission takes several decades, and the life of the human body is not enough. in this way. The theory of proliferation does not make sense here. So how is the long-distance transmission of intracellular signals realized? A recent study by two scientists, Cheng Xianrui and James Ferrer, of Stanford University School of Medicine, unraveled the mystery of biology—the death signal is transmitted intracellularly in the form of a trigger wave. The trigger wave is a self-enhancing reaction—diffuse wave, which is different from simple diffusion, its propagation speed is constant, and the signal strength is not attenuated. If the phenomenon of diffusion is seen as an animal feeding in the forest, the trigger wave is a spark. The power of the animal will gradually be consumed, and the walking speed will be slower and slower. Because the plants can ignite each other, the fire is maintained by this positive feedback. The trigger wave generation condition, in addition to positive feedback, also has a spatial coupling mechanism. "We have noticed that there are positive feedbacks in many cytoplasmic components involved in apoptosis, and substances can be exchanged between different regions of the cytoplasm. Therefore, cytoplasm can be a medium for triggering waves." Cheng Xianrui, who is far away from the United States, accepts the Science and Technology Daily. In an e-mail interview, it was said that the speed of the trigger wave was constant, and it was much faster than the spread in long-distance propagation. Therefore, they proposed that the mechanism of apoptosis is the trigger wave hypothesis and try to verify it by experiment. Turn off the lights once and solve the problem The study used the egg cells of Xenopus laevis, which is about 1300 microns in diameter, more than 100 times that of normal somatic cells. This large volume provides ample space for long-distance transmission of the signal, and it is convenient for the researcher to distinguish whether the diffusion or the triggering wave is working. The scientists placed the extracted cytoplasm in a very thin transparent tube and used a fluorescent probe to label the activated caspase to detect the transmission of apoptosis in space. After artificially triggering apoptosis, it can be clearly seen that the fluorescent spot moves from one end of the long tube to the other. It has been estimated that the transfer speed is 30 microns per minute and does not change with the transfer distance. To rule out the illusion that this is just a cytoplasm into the long tube, scientists continue to study intact egg cells. However, because this cell is opaque, fluorescent labeling will not work, then how to observe the transmission of death signals? This problem has plagued Cheng Xianrui for several months. Until one day, he turned off the fluorescent light in the laboratory to watch the fluorescent signal, and placed the cells under the ordinary fluorescent light and observed it with a microscope. A magical phenomenon appeared in front of the eyes: the cells that are apoptotic, and the surface has a ring of dark colors. Ripple, moving from side to side. Further research found that this surface wave starts at the trigger point of apoptosis, and the propagation speed is consistent with the previous long tube test results, which proves that the trigger wave is the propagation mechanism of intracellular apoptosis signal. In addition to apoptosis, trigger waves are also closely related to mitosis and transmission of neural signals. Since the positive feedback and coupling mechanisms it relies on are very common in biological regulation, it seems to James that in the future, the existence of trigger waves will be seen in more life phenomena, which is the research direction after the experimental team. Cheng Xianrui told the Science and Technology Daily: "Many biologists have not heard of trigger waves, but I believe that in the near future, it will appear in textbooks." Access Control System,Door Access Control System,Door Entry Systems,Door Access System Zhuhai Mingke Electronics Technology Co., Ltd , https://www.zhmkdz-electronics.com